As a microprocess technology, such a photolithographic technology that a negative photosensitive resin is subjected to exposure and development to form a structure (fine structure) having a fine pattern is known. This technology is used in a wide variety of applications to, for example, production of semiconductor integrated circuits, production of masks for semiconductor exposure and production of various MEMSs (micro electro mechanical systems). As an example of the application to the production of the MEMS, it has been increasingly practically applied in various small-scale sensors, micro-probes, thin film magnetic heads, ink jet recording heads, etc. A stepper using i-line as a light source is widely used as a device for conducting exposure. In the field of this technology, it has been required in recent years to produce a structure having a more complicated and finer structure, and there has thus been a demand for development of a negative photosensitive resin capable of forming a fine structure exhibiting high accuracy to light from a light source through a photomask.
Patent Literature 1 discloses, as a negative photosensitive resin, a photosensitive resin composition containing a polyfunctional epoxy resin and a cationic polymerization initiator.
Patent Literature 2 discloses an ink jet head for production of an MEMS, including a nozzle which ejects an ink droplet by allowing a bubble formed by heating a heating resistor to communicate with the air. This patents also discloses, as a covering resin used for forming an ink flow path wall of this ink jet head, a resin composition containing an epoxy resin that is solid at ordinary temperature as a main component.